Underfeed stoker for boilers.



E K. STANDISH & G. E. STEVENS.

UNDERFEED STOKER FOR BOILERS. APPLICATION FILED NOV. 28. 1913..

Patented Jul 17, 1 917.

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ATTORNEY.

at Stoughton,

t1 tE EDWARD K. STANDISH, OF STOUGHTON, AND GEORGE E. STEVENS, OF EVERETT, MASSA- CHUSETTS, ASSIGNORS TO STEVENS MANUFACTURING ASSOCIATION, OF BOSTON,

MASSACHUSETTS.

UNDERFEED STOKER FOR BOILERS.

Specification of Letters Patent.

Patented July 17, 1917.

Application filed November 28, 1913. Serial No. 803,386.

To all whom it may concern:

Be it known that we, EDWARD K. STAN- DISH, a citizen of the United States, residing in the county of Norfolk and the State of Massachusetts, and GEORGE E. STEVENS, a citizen of the United States, residing at Everett, in the county of Middlesex and the State of Massachusetts, have jointly invented a new and useful Improvement in Underfeed Stokers for Boilers, of which the" following is a specification.

Our invention relates to improvements in mechanical stokers in which coal isca-rried into a fire chamber underneath a boiler by means of a shaft having cast on it a screw thread broken at intervals; and the objects of our improvements are, first, to mechanically deposit coal on the grates of a boiler; second, to provide means for doing so in such a manner as will insure an even distribution on the grates; third to afiord facilities for the running of any one stoker independently of the other, when there is more than one on a single driving shaft; fourth, to provide a means of taking down any working part and replacing it without removing the whole machine, or affecting the fire; fifth, to provide for the greatest amount of space for the passage of air to the fire.

\Ve attain these objects by the mechanism shown in the accompanying drawing.

These improvements in part consisting of a one-piece cast conveyer worm, and shaft, the worm being broken at intervals in order to heap the coal, flexibly connected to the driving mechanism; also the flexible mounting of said worm; the U shaped trough having a reduced opening at the top, thus increasing the grate area; the open and adjustable steady rest in the middle of said worm; a casing having an oil and dust tight chamber inclosing the driving mechanism and worm thrust devices; the placing of the driving Worm above instead of below the worm wheel thus making possible the retention of oil in said chamber; the flexible connection between each driving worm thus eliminating the absolute accuracy necessary with a single shaft having a large number of bearings close together and liable to get out of line from the buckling of the front, or otherwise; the sliding clutch forming a part of the flexible connection; and a construction allowing the removal and replacing of all the moving parts ofsaid stoker without the necessity of entering the firebox or removing the fire.

In the drawings Figure 1 is a view, partly in section, looking at the front of a boiler; and discloses the driving worm, the worm clutch, and the flexible connection between the two c0nveyer heads.

Fig. 2 is a section on line A B. Fig. 1, showing the construction of this type of flexible connector.

Fig. 3 is a sectional elevation of the stoker disclosing a one-piece cast worm with broken sections, and flexibly mounted, and shows the driving mechanism and thrust devices.

Fig. 4 is a section of the rotary feed shaft showing the driving dogs adapted to fit into thedriving worm wheel.

Fig. 5 is a section on line C. D. of the trough in Fig. 3 and shows a detail of a type of steady rest shown in side view in Fig. 3, also a section of a trough having straight sides and a reduced opening at the top.

Fig. 6 is a section on line E. F. Fig. 3, showing a U shaped trough having a reduced opening at the top, and also the worm end bearing elongated and slotted at the to ln the preferred type of construction herein selected for illustration number 1, Fig. 1 is the driving shaft mounted in. bearings 2 and 3 of the conveyer head 4, and having mounted thereon the drive worm 5 meshing with the worm wheel 6, shown in Fig. 3, which rotates on the removable bearing 7, which forms a tight wall between the oil chamber 8 and the coal chamber 9 of the casing 4; said worm wheel 6 by means of dogs 10 such as are shown in Fig. 4, driving the conveyer worm 11, which is flexibly mounted thereon, being centrally located by the ring 12 caston said worm and fitting the interior of "the worm wheel 6. \Vhile the type of dogs disclosed in Fig. 4: take up a small amount of room the dogging method shown in Fig. 1, parts 29 and 30, or an adaptation of this type, could be used.

These constructions would both allow a limited eccentric movement of the conveyer worm 11 in the event of the presence of foreign material such as iron between the worm and the outer casing, the elongated slot 18, Fig. 6, allowing the worm to float above the bearing if necessary. In Figs. 3,. 5, and 6, the trough-21, has openings 33 on its top edge thus enlarging the grate area.

Wehave found after repeated experiments that this peculiar type of trough with the perforations at the top,will allow a free distribution of the air just above the trough as it relieves to an appreciable extent the effect on the fire produced by lack of air as the green coal boils in from the.conveyer.

This is our preferred form.

of the fire box.

The casing 4, Fig. 3, is separate from that portion of the trough 21 inside the boiler front and may be removed by removing the bolts 14, or as designed the removal of the the worm wheel 6, the bearing 7, the packing washer which is preferably made of easing cover head cap 15 will allow the removal and replacing of the conveyer Worm thrust washers 16 in said cap 15, and also felt, and the conveyer worm 11, While the removal of the cap 17 will allow the removal of the drive worm 5, the shaft 1, the clutch and the flexible connection.

It will thus beseen that all of the movable parts ;of this stoker can be removed and replaced without shutting down a ,boiler, as with the construction used a good fire can-be maintained without using or re- IIlOVlIlg the stoker by simply lifting out the j coal hoppenfjlS and shoveling coal through the doors 19 in the usual manner.

Shouldthe steady rest 20, Fig. 5., be used the conveyer worm 11 maystill be removed by rotating the worm.

The steady rest, as disclosed in Fig. 5 consists of screws 20 threaded through holes in the trough 21 and having bearing plates 22, on their inner ends resting against the ring 23,, Fig. 3, cast and turned on the conveyer worm 11, said screws 20 having lock nuts 24 outside said trough.

Each. conveyer may be. independently stopped by throwing the lever 26, Fig. 1, releasing the clutch 27 from engagement with corresponding jaws onthe drive worm '5, the clutch 27 being keyed to the shaft 1 and having on its opposite end a. chamber 28 adapted to--hold one end of the dumbbell shaped piece29 which has projecting studs: 30 on each end meshing in the slots 31 of thecluteh 27 and of the shaft 1, and adapted to do the driving even though the two shafts are not in line.

Should the clutch 27 not be used the chamber 28 would take the placeof the jaws at In Fig. 3, 34rlS-th6fi1'8 wall at the end- In Fig. 6 the top of the. elongated bearing 13 is preferably left open as shown at 32 in order to easily'clean the bearing if desired. An important point in this construction is the placing of the driving shaft 1 above instead of below the worm wheel 6, as we have found by experience that the retention of oil in the chamber 8 is much harder to accomplish when the shaft 1 is below, and also that mechanical inaccuracies and wear tend to cause the worm and worm wheel to bind where said shaft is below; also greater access to the ash pit doors is secured when the shaft is above and the removal and replacing of the parts is easier to accomplish.

Like numbers in the drawings refer to the same. parts in all the figures.

' Having thus described the type or embodiment of the invention herein selected for illustration we wish it understood that the terms are used in a descriptive sense and not for purposes of limitation, the invention being set forth inthe following claims;

1. In an underfeed stoker for boilers the combination of a driving mechanism withof the fuel conveyer shaft, together with the bearing 13 permitting vertical movement of the conveyer shaft and a fuel trough all substantially as described or shown.

2. In an underfeed stoker for boilers the combination of a driving mechanism consisting of a driving worm and a worm gear meshing, with it, so as to permit the conveyer shaft to be driven by means of a flexible connection consisting of a dogging device, a part of which is formed upon the interior of the driven gear and a part upon the fuel conveyer shaft, a conveyer shaft, a steady rest of open construction protecting the conveyer shaft near the sides and bottom a bearing 13 permitting a vertical movement of the fuel conveyer shaft and a fuel trough substantially as shown or described. EDWARD K. STANDISI-I.

GEORGE E. STEVENS. Witnesses:

CHAS. ALLEN TABER, Lomsn D. BUZZELL. 

